Bearing ring for fixing a mounting block on the progressively variable curved finished face of a semi-finished lens or mold blank

Claim 1

A bearing ring for semi-finished ophthalmic lens or lens mold blanks having progressive convex faces of different curvature, said bearing ring comprising a plurality of bearing areas for contact with any selected one of a plurality of different semi-finished blanks within a selected range, said bearing areas being circumferentially spaced around an axis, said bearing ring having a reference plane perpendicular to said axis and axially inwardly of said bearing areas, all of said bearing areas being generally inclined relative to said reference plane, each of said bearing areas extending between two bearing areas ends radially and axially offset relative to each other, each of said bearing areas having a median plane containing said axis and extending radially through a middle of said bearing area, planes tangential to respective ends of each of said bearing areas and orthogonal to said medial plane forming an obtuse dihedron having a concave side facing towards said reference plane, each of said bearing areas comprising a plurality of bearing facets for selective contact with a semi-finished blank, all of said bearing facets being generally inclined relative to said reference plane and all being orthogonal to the corresponding median plane, the inclination of each of said bearing facets of each of said bearing areas being different from that of other bearing facets of the same bearing area, said bearing facets being in radial succession on circumferences of different diameter according to their inclination, end bearing facets of each of the bearing areas being coincident with corresponding end tangential planes.